1. Field of the Invention
The present invention relates in general to techniques for predicting or estimating a minimum stopping distance of a running vehicle, which is required to stop the running vehicle by brake application.
2. Discussion of the Related Art
As disclosed in JP-A-52-38977, there is known a technique for calculating the minimum stopping distance X, which is required to stop a running vehicle by activation of a braking system thereof, by the following equation, and indicating the calculated minimum stopping distance X:
X=V.sup.2 /(2 .mu.g) PA1 V: brake application vehicle speed (running speed at the time when the braking system starts to be activated) PA1 .mu.: friction coefficient of a roadway surface on which the vehicle is running PA1 g: gravitational acceleration PA1 a step of obtaining measurement data for each of at least one sample vehicle which is braked by a braking system thereof operated with its full braking capacity, the at least one sample vehicle including at least one of a vehicle different in type from the subject vehicle and a vehicle identical in type with the subject vehicle but different in specification from the subject vehicle, the measurement data including a weight of the each sample vehicle, a running speed of the each sample vehicle when the braking system of the each sample vehicle starts to be activated, a stopping distance through which the each sample vehicle has run to be stopped, a radius of a tire of the each sample vehicle, and optionally an axial width of the tire of the each sample vehicle; PA1 a step of obtaining at least one predicting equation on the basis of the measurement data in a statistical manner, the at least one predicting equation providing a predicted value of the minimum stopping distance on the basis of a weight of the subject vehicle, a running speed of the subject vehicle when the braking system of the subject vehicle starts to be activated, a radius of a tire of the subject vehicle, and optionally an axial width of the tire of the subject vehicle; and PA1 a step of calculating the predicted value of the minimum stopping distance of the subject vehicle, by substituting into one of the at least one predicting equation, the weight of the subject vehicle, the running speed of the subject vehicle, the radius of the tire of the subject vehicle, and optionally the axial width of the tire of the subject vehicle, so that the one predicting equation provides the predicted value of the minimum stopping distance. PA1 D1 represents the weight of the subject vehicle; PA1 D2 represents the axial width of the tire of the subject vehicle; PA1 D3 represents the radius of the tire of the subject vehicle; PA1 D4 represents the running speed of the subject vehicle; and PA1 D5 represents the minimum stopping distance of the subject vehicle. PA1 a step of obtaining measurement data for each of at least one sample vehicle which is driven at the first nominal speed and then braked by a braking system thereof operated with its full braking capacity, and which is driven at the second nominal speed and then braked by the braking system operated with its full braking capacity, the at least one sample vehicle including at least one of a vehicle different in type from the subject vehicle and a vehicle identical in type with the subject vehicle but different in specification from the subject vehicle, the measurement data including a weight of the each sample vehicle, a first running speed of the each sample vehicle when the braking system of the each sample vehicle starts to be activated during running of the each sample vehicle at the first nominal speed, a second running speed of the each sample vehicle when the braking system of the each sample vehicle starts to be activated during running of the each sample vehicle at the second nominal speed, a first stopping distance through which the each sample vehicle has run to be stopped where the each sample vehicle is driven at the first nominal speed, a second stopping distance through which the each sample vehicle has run to be stopped where the each sample vehicle is driven at the second nominal speed, a radius of a tire of the each sample vehicle, and optionally an axial width of the tire of the each sample vehicle; PA1 a step of obtaining at least one first predicting equation and at least one second predicting equation on the basis of the measurement data in a statistical manner, the at least one first predicting equation providing a predicted value of a first minimum stopping distance required to stop the subject vehicle where the subject vehicle is driven at the first nominal speed, on the basis of a weight of the subject vehicle, a first running speed of the subject vehicle when the braking system of the subject vehicle starts to be activated during running of the subject vehicle at the first nominal speed, a radius of a tire of the subject vehicle, and optionally an axial width of the tire of the subject vehicle, the at least one second predicting equation providing a predicted value of a second minimum stopping distance required to stop the subject vehicle where the subject vehicle is driven at the second nominal speed, on the basis of the weight of the subject vehicle, a second running speed of the subject vehicle when the braking system of the subject vehicle starts to be activated during running of the subject vehicle at the second nominal speed, the radius of the tire of the subject vehicle, and optionally the axial width of the tire of the subject vehicle; PA1 a step of calculating the predicted value of the second minimum stopping distance, by substituting, into one of the at least one second predicting equation, the weight of the subject vehicle, the second running speed, the radius of the tire of the subject vehicle, and optionally the axial width of the tire of the subject vehicle, so that the one second predicting equation provides the predicted value of the second minimum stopping distance; PA1 a step of calculating the predicted value of the first minimum stopping distance, by substituting, into one of the at least one first predicting equation, the weight of the subject vehicle, the first running speed, the radius of the tire of the subject vehicle, and optionally the axial width of the tire of the subject vehicle, so that the one first predicting equation provides the predicted value of the first minimum stopping distance; and PA1 a step of obtaining the decelerating section distance by subtracting the predicted value of the second minimum stopping distance from the predicted value of the first minimum stopping distance. PA1 a step of detecting a distance between the subject vehicle and the leading vehicle; and PA1 a step of estimating the running speed of the leading vehicle on the basis of the first running speed and a rate of change of the distance between the subject vehicle and the leading vehicle. PA1 a data obtaining device for obtaining a weight of the subject vehicle, a running speed of the subject vehicle, a radius of a tire of the subject vehicle, and optionally an axial width of the tire of the subject vehicle; PA1 a memory device for storing therein at least one predicting equation for providing a predicted value of the minimum stopping distance on the basis of the weight, the running speed when the braking system of the subject vehicle starts to be activated, the radius, and optionally the axial width; and PA1 a stopping-distance predicting device for providing the predicted value of the minimum stopping distance, by substituting the weight, the running speed, the radius, and optionally the axial width, into one of the at least one predicting equation. PA1 an apparatus defined in mode (10); PA1 an actuator for changing the running state of the subject vehicle; PA1 a control device for controlling the actuator on the basis of the minimum stopping distance which has been predicted by the apparatus defined in mode (10), such that a distance between the subject vehicle and an object which exists ahead of the subject vehicle is held equal to or larger than the minimum stopping distance. PA1 an apparatus defined in mode (10); PA1 an actuator for changing the running state of the subject vehicle; PA1 a detecting device for detecting a distance between the subject vehicle and the leading vehicle; PA1 an estimating device for estimating a running speed of the leading vehicle on the basis of the running speed of the subject vehicle and a rate of change of the distance between the subject vehicle and the leading vehicle; PA1 a decelerating-section-distance predicting device for predicting a decelerating section distance through which the subject vehicle runs while being decelerated by the braking system operated with its full braking capacity from the running speed of the subject vehicle to the running speed of the leading vehicle, on the basis of the predicted value of the minimum stopping distance of the subject vehicle and a predicted value of the minimum stopping distance of the leading vehicle which value is obtained by substituting the weight, the running speed of the leading vehicle, the radius, and optionally the axial width into one of the at least one predicting equation; and PA1 a control device for controlling the actuator on the basis of the decelerating section distance, such that the distance between the subject vehicle and the leading vehicle is held equal to or larger than the decelerating section distance. PA1 D1 represents the weight of the subject vehicle, PA1 D2 represents the axial width of the tire of the subject vehicle, PA1 D3 represents the radius of the tire of the subject vehicle, PA1 D4 represents the running speed of the subject vehicle, and PA1 D5 represents the minimum stopping distance of the subject vehicle.
where,
The present inventor found out a fact that the minimum stopping distance can be predicted more accurately by taking into account at least the weight of the vehicle, the radius of a tire of the vehicle and the brake application vehicle speed.